59 lines
2.3 KiB
Diff
59 lines
2.3 KiB
Diff
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From: Prasad J Pandit <pjp@fedoraproject.org>
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Date: Thu, 4 Jun 2020 14:38:30 +0530
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Subject: ati-vga: check mm_index before recursive call (CVE-2020-13800)
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MIME-Version: 1.0
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Content-Type: text/plain; charset=UTF-8
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Content-Transfer-Encoding: 8bit
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Git-commit: a98610c429d52db0937c1e48659428929835c455
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References: bsc#1172495, CVE-2020-13800
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While accessing VGA registers via ati_mm_read/write routines,
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a guest may set 's->regs.mm_index' such that it leads to infinite
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recursion. Check mm_index value to avoid such recursion. Log an
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error message for wrong values.
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Reported-by: Ren Ding <rding@gatech.edu>
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Reported-by: Hanqing Zhao <hanqing@gatech.edu>
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Reported-by: Yi Ren <c4tren@gmail.com>
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Message-id: 20200604090830.33885-1-ppandit@redhat.com
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Suggested-by: BALATON Zoltan <balaton@eik.bme.hu>
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Suggested-by: Philippe Mathieu-Daudé <philmd@redhat.com>
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Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org>
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Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
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Signed-off-by: Bruce Rogers <brogers@suse.com>
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---
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hw/display/ati.c | 10 ++++++++--
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1 file changed, 8 insertions(+), 2 deletions(-)
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diff --git a/hw/display/ati.c b/hw/display/ati.c
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index 58ec8291d4601b70720fa1484f88..9228f1b242bb7b141eb50a19e12b 100644
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--- a/hw/display/ati.c
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+++ b/hw/display/ati.c
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@@ -285,8 +285,11 @@ static uint64_t ati_mm_read(void *opaque, hwaddr addr, unsigned int size)
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if (idx <= s->vga.vram_size - size) {
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val = ldn_le_p(s->vga.vram_ptr + idx, size);
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}
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- } else {
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+ } else if (s->regs.mm_index > MM_DATA + 3) {
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val = ati_mm_read(s, s->regs.mm_index + addr - MM_DATA, size);
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+ } else {
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+ qemu_log_mask(LOG_GUEST_ERROR,
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+ "ati_mm_read: mm_index too small: %u\n", s->regs.mm_index);
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}
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break;
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case BIOS_0_SCRATCH ... BUS_CNTL - 1:
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@@ -520,8 +523,11 @@ static void ati_mm_write(void *opaque, hwaddr addr,
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if (idx <= s->vga.vram_size - size) {
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stn_le_p(s->vga.vram_ptr + idx, size, data);
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}
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- } else {
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+ } else if (s->regs.mm_index > MM_DATA + 3) {
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ati_mm_write(s, s->regs.mm_index + addr - MM_DATA, data, size);
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+ } else {
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+ qemu_log_mask(LOG_GUEST_ERROR,
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+ "ati_mm_write: mm_index too small: %u\n", s->regs.mm_index);
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}
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break;
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case BIOS_0_SCRATCH ... BUS_CNTL - 1:
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